Some drugs are metabolized by cytochrome P450 monooxygenase, leading to unfavorable pharmacokinetics and the need for more frequent and higher doses than are most desirable. Administration of such drugs with an agent that inhibits metabolism by cytochrome P450 monooxygenase will improve the pharmacokinetics (i.e., increase half-life, increase the time to peak plasma concentration, increase blood levels) of the drug.
It has been discovered that coadministration of compounds of formula I with a drug which is metabolized by cytochrome P450 monooxygenase, especially the P450 3A4 isozyme, causes an improvement in the pharmacokinetics of such a drug.